From patchwork Mon Mar 16 22:30:42 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Sven Eckelmann X-Patchwork-Id: 229384 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-9.9 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU, HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH, MAILING_LIST_MULTI, SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,USER_AGENT_GIT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id B763DC18E5B for ; Mon, 16 Mar 2020 22:31:12 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 8A57920663 for ; Mon, 16 Mar 2020 22:31:12 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=narfation.org header.i=@narfation.org header.b="uUO/YNwk" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1732743AbgCPWbM (ORCPT ); Mon, 16 Mar 2020 18:31:12 -0400 Received: from dvalin.narfation.org ([213.160.73.56]:49114 "EHLO dvalin.narfation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1732770AbgCPWbM (ORCPT ); Mon, 16 Mar 2020 18:31:12 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=narfation.org; s=20121; t=1584397870; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=u5BoueoSl316g9BlxCBkJUAnvid4QVrNKbHZ1C1V7kA=; b=uUO/YNwkEijOfzANOGNYAd7SED/N2rhDSHzukcIkMf8GewlmNOEHDFD2z2guDgkWETZBZK 8Q2pZo3mbScOJiv3hQvpbnd9GEsm+46hXlryjqRiRFQ+P06xomgN7mDvTYOTRQL0CSmN6L mgSQAtGoP9uHIUsJh8V7OPQtubljUoQ= From: Sven Eckelmann To: stable@vger.kernel.org Cc: Sven Eckelmann , Simon Wunderlich Subject: [PATCH 4.9 01/24] batman-adv: Fix double free during fragment merge error Date: Mon, 16 Mar 2020 23:30:42 +0100 Message-Id: <20200316223105.6333-2-sven@narfation.org> X-Mailer: git-send-email 2.20.1 In-Reply-To: <20200316223105.6333-1-sven@narfation.org> References: <20200316223105.6333-1-sven@narfation.org> MIME-Version: 1.0 Sender: stable-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org commit 248e23b50e2da0753f3b5faa068939cbe9f8a75a upstream. The function batadv_frag_skb_buffer was supposed not to consume the skbuff on errors. This was followed in the helper function batadv_frag_insert_packet when the skb would potentially be inserted in the fragment queue. But it could happen that the next helper function batadv_frag_merge_packets would try to merge the fragments and fail. This results in a kfree_skb of all the enqueued fragments (including the just inserted one). batadv_recv_frag_packet would detect the error in batadv_frag_skb_buffer and try to free the skb again. The behavior of batadv_frag_skb_buffer (and its helper batadv_frag_insert_packet) must therefore be changed to always consume the skbuff to have a common behavior and avoid the double kfree_skb. Fixes: 610bfc6bc99b ("batman-adv: Receive fragmented packets and merge") Signed-off-by: Sven Eckelmann Signed-off-by: Simon Wunderlich --- net/batman-adv/fragmentation.c | 8 +++++--- net/batman-adv/routing.c | 6 ++++++ 2 files changed, 11 insertions(+), 3 deletions(-) diff --git a/net/batman-adv/fragmentation.c b/net/batman-adv/fragmentation.c index a06b6041f3e0..384a1014da07 100644 --- a/net/batman-adv/fragmentation.c +++ b/net/batman-adv/fragmentation.c @@ -232,8 +232,10 @@ static bool batadv_frag_insert_packet(struct batadv_orig_node *orig_node, spin_unlock_bh(&chain->lock); err: - if (!ret) + if (!ret) { kfree(frag_entry_new); + kfree_skb(skb); + } return ret; } @@ -305,7 +307,7 @@ batadv_frag_merge_packets(struct hlist_head *chain) * * There are three possible outcomes: 1) Packet is merged: Return true and * set *skb to merged packet; 2) Packet is buffered: Return true and set *skb - * to NULL; 3) Error: Return false and leave skb as is. + * to NULL; 3) Error: Return false and free skb. * * Return: true when packet is merged or buffered, false when skb is not not * used. @@ -330,9 +332,9 @@ bool batadv_frag_skb_buffer(struct sk_buff **skb, goto out_err; out: - *skb = skb_out; ret = true; out_err: + *skb = skb_out; return ret; } diff --git a/net/batman-adv/routing.c b/net/batman-adv/routing.c index 8b98609ebc1e..f9ffb1825f6d 100644 --- a/net/batman-adv/routing.c +++ b/net/batman-adv/routing.c @@ -1080,6 +1080,12 @@ int batadv_recv_frag_packet(struct sk_buff *skb, batadv_inc_counter(bat_priv, BATADV_CNT_FRAG_RX); batadv_add_counter(bat_priv, BATADV_CNT_FRAG_RX_BYTES, skb->len); + /* batadv_frag_skb_buffer will always consume the skb and + * the caller should therefore never try to free the + * skb after this point + */ + ret = NET_RX_SUCCESS; + /* Add fragment to buffer and merge if possible. */ if (!batadv_frag_skb_buffer(&skb, orig_node_src)) goto out;